CSS - Resize white background image

I am trying to carry out the "Build a Tribute Page" challenge on the Free Code Camp.

However, I run into a problem in css. I want the size of the white box of an image to be smaller than what I see. But I do not know exactly what to modify. On the other hand I do not know exactly how to google the term I need. The image of what I have:

The code where the image is:

  .image {
    display: block;
    padding: 2px;
    margin-bottom: 40px;
    line-height: 1.42857143;
    background-color: #fff;
    border: 1px solid #ddd;
    border-radius: 4px;
  }

The HTML of the image is as follows:

<div class="image">
  <img 
    src="http://www.subeimagenes.com/img/los-simuladores-tlf-723143.jpg"
    alt="panflet">
  <div class="captiontext">
The four assosiates: Mario Santos, Emilio Ravenna, Pablo Lampone, Gabriel Medina    
  </div>
</div>

Code of the entire project in Code Pen

Thank you!